Locking devices for the columns of presses are known, said locking devices comprising locking clamps mounted on said moving plane and engaged in said columns.
Said locking devices comprise two pairs of said locking clamps, the clamps of each pair being aligned on the horizontal or vertical plane and engaged in corresponding columns, and at least one pair of connection rods for each pair of said clamps.
Each clamp of a pair is connected to the clamp of the other pair that is in a corresponding position by means of at least one of said connection rods. In particular, each pair of clamps comprises a so-called inner clamp, meaning that it faces the other pair, and an outer clamp, meaning that it faces outwards.
The inner clamp of a pair is connected with the external clamp of the other pair through at least one of said rods.
Said locking device also comprises an actuator included between said two pairs of clamps, said actuator acting on both said inner clamps of said two pairs in order to open and close the two pairs of clamps at the same time. After closing the mould, translating said moving plane towards said fixed plane means making said actuator close the clamps that thus clamp said columns.
Once the clamps are closed, the columns are placed under traction by loading them axially in order to exert a compression force on the mould. Said actuator generally comprises a cylinder hinged to two arms, each arm being respectively hinged to one of said inner clamps, wherein the translational motion of the cylinder rod is transmitted to said clamps by means of said arms.
Therefore, each one of said locking elements has a fixed point with respect to said moving plane, wherein said fixed point is located between the inner clamps, at the level of a connection mechanism that connects the two inner clamps.
Said clamps of each pair, on the other hand, are not directly connected to each other, being simply constrained so that they slide on the same plane via guides which are integral with said moving plane.
Therefore, the synchronization of the clamps of each pair is carried out by said mechanism and by said rods that transmit motion from the inner clamp of one pair to the outer clamp of the other pair, while between the two clamps of the same pair there is no direct mechanical connection.